Project Summary/Abstract Overweight and obesity account for 8-17% of all cancers in adults, and the increasing prevalence of overweight and obesity in the US over the past 3 decades poses a major challenge to cancer prevention efforts. Dietary modification will be necessary to achieve weight loss at the population level, but studies have shown that only a small minority of dieters successfully maintain meaningful weight loss beyond one year of starting a diet. Though weight loss is affected by many factors, poor behavioral adherence to nutritional targets appears to be the foremost obstacle to weight loss. Therefore, the objective of this project is to identify psychological and behavioral factors that undermine individuals'abilities to adhere to a weight loss diet. Mounting evidence from the fields of neuroscience and behavioral science indicates that the pleasure and reward associated with palatable food play a substantial role in the etiology of obesity and may interfere with the ability to refrain from palatable, energy-dense foods while dieting. We will determine whether the degree to which individuals respond psychologically to the immediately rewarding effects of palatable food predicts the ability to adhere to a weight loss diet. Eighty-five healthy, overweight or obese women will complete behavioral and self-report measures quantifying sensitivity to the rewarding effects of food. Participants will then receive nutritional counseling and be asked to follow an energy expenditure-adjusted weight loss diet. Nutritional analysis of weighed food records will be performed to determine adherence to individualized nutritional targets for energy, fruit, vegetable, and saturated fat intake. Statistical analyses will test the proposed associations between psychological responses to immediate food reward and diet adherence. The expected pattern of findings would highlight the need to address reward-driven eating in interventions for weight loss and cancer prevention.